In the automatization of spinning operations and especially in the automatic formation of yarn whereby roving bobbins from a roving frame are subjected to spinning on a ring-spinning frame, it has been increasingly important to reduce the cost. This mandates specification of certain requirements. One of these requirements is that the thread or yarn from the roving bobbin be automatically extracted, easily, while the roving bobbin as a whole remains stable and can be handled without loss of capacity to automatically extract the roving or strand. This requirement has primarily been satisfied in the past by depositing at least a partial turn of stubbing, at the conclusion of the winding of the roving body, on a lower winding cone and thereafter separating or breaking the roving slubbing to allow doffing of the roving bobbin. The result is that the roving bobbins can be easily transferred and handled in the mounting of the bobbins in the creel of a ring-spinning machine. That means that an extraction of the slubbing from the bobbin downwardly directly should be possible to allow the bobbin to be tied into the yarn formed in the spinning machine.
There are systems in which the separation of the roving slubbing is a requirement for the automatic removal of full roving bobbins (EP 0 409 755 B1). The process of this patent is satisfactory for long fibers in which, upon stopping of the flyers, the respective pressing fingers can lie against the lower conical regions of the respective bobbins to give rise to a partial opening of the roving slubbing. In this case, a partial rotation of the bobbin is effected while the flyer is held stationary and the roving slubbing is broken. The bobbin can then be removed from the bobbin rail.
Another prior arrangement for this purpose has been described in EP 0 698 678 A1. In the process and apparatus described here, the roving slubbing is separated. This process is so carried out that after the end of the spinning of the roving bobbin, the latter is raised until the pressing finger is guided against the lower cone portion of the bobbin. The roving bobbin is then rotated together with the flyer and the feed from the drafting frame is effected so as to generate a high tension in the winding formed on the roving bobbin.
The roving bobbin is then dropped relative to the flyer to separate oncoming slubbing from the roving bobbin in the region between the winding region and the flyer. Reference may be had also to the process and apparatus described in JP Hei-7-11524-A in which, after the termination of the winding of the body of roving, the pressing finger and the bobbin rail are displaced into an opposite position in which a separation of the roving slubbing is not effected. Then in this position the flyer and the roving bobbin are again set into operation whereby a separation of the roving slubbing automatically is effected.